Respiratory system
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Transcript Respiratory system
The Digestive System
and Body Metabolism
Premedical Biology
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
The Digestive System and Body
Metabolism
Digestion
Breakdown of ingested food
Absorption
Passage of nutrients into the blood
Metabolism
Production of cellular energy (ATP)
Organs of the Digestive System
Organs of the Alimentary Canal
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Mouth (Oral Cavity) Anatomy
Lips (labia)
Cheeks
Hard palate
Soft palate
Uvula
Mouth (Oral Cavity) Anatomy
Vestibule
Oral cavity
Tongue
Mouth (Oral Cavity) Anatomy
Tonsils
Palatine tonsils
Lingual tonsil
Processes of the Mouth
Mastication (chewing) of food
Mixing food with saliva – ptyalin (amylase)
Initiation of swallowing by the tongue
Allowing for the sense of taste
Sweet, sour, bitter, tangy, spicy,
taste buds
nerve cells
10,000 taste cells
papillae
cover the tongue, palate,
epiglottis, and pharynx
Each taste cell consists of small
hairs that lie in the taste pore.
There, dissolved food or drink
binds to a receptor, like a key in
a lock.
Pharynx Anatomy
Nasopharynx –
not part of the
digestive system
Oropharynx
Laryngopharynx
Layers of Alimentary Canal Organs
Mucosa
Surface epithelium
Small amount of connective tissue
(lamina propria)
Small smooth muscle layer
Layers of Alimentary Canal Organs
Submucosa
Soft connective tissue with blood
vessels, nerve endings, and lymphatic
tissue
Layers of Alimentary Canal Organs
Muscularis externa – smooth muscle
Inner circular layer
Outer longitudinal layer
Serosa
Outermost layer – visceral peritoneum
Layer of serous fluid-producing cells
Stomach Anatomy
the cardioesophageal sphincter
Regions
Cardiac region – near the heart
Fundus
Body
Phylorus –terminal end
the pyloric sphincter
Stomach Anatomy
Stomach functions and Mucosa
storage tank, chemical breakdown
chyme (processed food)
Gastric pits formed by folded mucosa
Simple columnar epithelium:
Mucous neck cells – produce a sticky alkaline
mucus
Gastric glands:
Stomach glands
• Chief cells – produce protein-digesting
enzymes (pepsinogens)
• Parietal cells – produce hydrochloric acid
• Endocrine cells – produce enteroglukagon,
gastrin, somatostatin
Glands and specialized cells are in the
gastric gland region
Structure of the Stomach Mucosa
Small Intestine
The body’s major digestive organ
Site of nutrient absorption into the blood
Duodenum
Jejunum
Ileum
Chemical digestion
Source of enzymes that are mixed with
chyme
Intestinal cells
Pancreas
Bile enters from the gall bladder
Chemical digestion
Microvilli of the Small Intestine
Folds and Villi of Mucose
Called circular folds - folds of the mucosa
and submucosa
Villi with blood and
lymphatic capillaries
The submucosa has
Peyer’s patches
(lymphatic tissue)
Microvilli of the Small Intestine
Microvilli found on absorptive cells
Digestion in the Small Intestine
Enzymes
Break double sugars into simple sugars
pancreatic amylase
Complete some protein digestion
exopeptidase and endopeptidase: trypsin,
chymotrypsin
Pancreatic enzymes play the major
digestive function (lipase)
Absorption in the Small Intestine
Water is absorbed along the length of
the small intestine
End products of digestion
Most substances are absorbed by active
transport through cell membranes
Lipids are absorbed by diffusion
Substances are transported to the liver
by the hepatic portal vein or lymph
Structures of the Large Intestine
Colon
Ascending
Transverse
Descending
S-shaped sigmoidal
Rectum
Anus – external body opening
Large Intestine
Functions of the Large Intestine
Absorption of water
Eliminates indigestible food from the
body as feces
Does not participate in digestion of food
Goblet cells produce mucus to act as a
lubricant
Resident bacteria digest remaining
nutrients
Accessory Digestive Organs
Salivary glands
Teeth
Pancreas
Liver
Gall bladder
Salivary Glands and Teeth
Saliva-producing glands
Parotid glands – located anterior to ears
Submandibular glands
Sublingual glands
Humans have two sets of teeth
Deciduous (baby or milk) teeth
Teeth
Permanent teeth
Replace deciduous teeth beginning
between the ages of 6 to 12
A full set is 32 teeth, but some people do
not have wisdom teeth
Classification of Teeth
Incisors
Canines
Premolars
Molars
Regions of a tooth
Crown – exposed
part
Outer enamel
Dentin
Pulp cavity
Neck
Region in contact
with the gum
Connects crown to
root
Liver
Largest gland in the body
Located on the right side of the body
under the diaphragm
Consists of four lobes suspended from
the diaphragm and abdominal wall
Connected to the gall bladder via the
common hepatic duct
Role of the Liver in Metabolism
Several roles in digestion
Plays a central role in metabolism
Detoxifies drugs and alcohol
Degrades hormones
Produce cholesterol, blood proteins
(albumin and clotting proteins)
Processes of the Digestive System
Peristalsis
Segmentation – moving
materials back and forth
to aid in mixing
Thank you for your attention
Campbell, Neil A., Reece, Jane
B., Cain Michael L., Jackson,
Robert B., Minorsky, Peter V.,
Biology, Benjamin-Cummings
Publishing Company, 1996 –
2010.